Hydrodynamics Study of Electrode Intrusion Effects in Hierarchical Interdigitated Flow Field Design for Vanadium Redox Flow Batteries

Abstract

In redox flow batteries (RFB), flow field design and electrode intrusion are major key factors in determining its performance. A well-optimized electrode intrusion and good flow field design ensure uniform distribution of reactants throughout the active cell area. This will provide a convective feed of reactants to the reaction zone and minimize pressure drop. In this article, the effects of the electrode intrusion on pressure drop and electrolyte distribution in electrode region in a hierarchical interdigitated flow field (HIFF) were measured with computational fluid dynamics (CFD) method. Active cell area of 105 mm × 105 mm with a channel width of 3 mm and rib for the above flow field had been compared with 102 mm × 102 mm channel width of 3 mm and rib for normal interdigitated flow field (IFF) design. Three different electrode intrusions: 0.5, 1, 1.5 mm, and compressed electrodes of 2.5 mm thickness were investigated in this study. Simulation results showed that as we increased electrode intrusion within the channels, pressure drop increased but on the other hand electrolyte circulation effects also increased. A hierarchical interdigitated flow field gives better electrolyte circulation in the electrode region as compared to a normal interdigitated flow field and this study has been a benchmark to design stack level VRFB systems.